Our TAZ 5 extruder motor is getting extremely hot. Our measured temperature on the motor after 1 hour into the print is 204°F (96°C). Is this normal? It seems extremely high considering the small load on the extruder motor. Our prints also fail when the temperature gets this hot (starts sputtering and stops extruding). Has anybody else run into this? Is this normal?
It can be. I know mine gets quite warm. Extruders do a suprising amount of work. You can also turn down the current to the motor in firmware, but that leads to slipping. i’d rather have to replace a $10 motor a bit more often than I might personally.
Thanks piercet! If the motor isn’t the cause of our prints failing, I don’t know what it could be. We just replaced the hotend + re-flashed the firmware to default and it still has the same problem. The print also starts failing at about the same time that the extruder motor hits 200°F, which might be coincidental. It just starts under-extruding and then stops extruding altogether. Do you have any ideas on what the problem could be?
It could just be a failing motor then. bearings fail more when it’s warm. Swap the motor out and see if its the problem?
Yeah, we came to the conclusion that it’s either the motor or the control board causing over heating in the motor. We ordered a new motor yesterday and will see if that solves it. If not, we’ll monitor the current coming from the board and see if it’s abnormal.
So…we replaced our Stepper Motor with a brand new one and it was still getting extremely hot (>90°C). From the specs we looked up the motor is rated to about 70°C, so it was still getting way too hot.
We decided to try switching the motor on the Rambo board to the 2nd slot (for Dual Extruders) and modifying the firmware so that the machine is using the 2nd slot (we switched the “E1” and “E0” plugs on the control board). This worked (we were able to print using the 2nd slot) but the Stepper Motor is still getting just as hot and our prints are failing.
We are now baffled. Our last resort is to buy a new Rambo board, but it’s a big gamble considering that they cost a few hundred bucks. Is there anybody out there that has a suggestion?
If you have a DVM measure the E0 REF and E1 REF test points near the driver chips(Carefully). It should read around .6 -.8 volts. This is the voltage that is used to determine the drive currents for the motors. if it is off then the Digipot is bad on the RAMBo.
That is what it sounds like is wrong.
So when the printer first starts up and is idle, the voltage reads about .75V. However, as soon as you start a print it jumps up to 1.6V (even when the extruder motor is not running). It also stays at 1.6V after the print is cancelled. You have to power the printer off & restart to get back to the .75V. What do you think?
That is FULL drive current to the stepper(1.6 volts) - it WILL get VERY HOT when that happens. It should not change value from idle to printing as if it just energizes them it will slowly cook the motor running that much current in the field winding. Only the Z drive needs that much current to run 2 motors in parallel.
You just might need to think about a new RAMBo. 
Yeah, we actually ordered a new board yesterday. Thanks for the help!!